Restoring the coronal plane alignment of the knee (CPAK) phenotype does not consistently improve patient-reported outcomes after primary total knee arthroplasty: A systematic review.
Sina Hajiaghajani, Mohammad Poursalehian, Amirhossein Salmannezhad et al.
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In 30 seconds
This systematic review assessed whether restoring preoperative coronal plane alignment of the knee (CPAK) phenotype, joint line obliquity (JLO), or arithmetic hip-knee-ankle angle (aHKA) is associated with better patient-reported outcomes after primary total knee arthroplasty. It included 13 studies: 1 randomised controlled trial, 1 prospective registry-based study, and 11 retrospective cohorts, with follow-up ranging from 1 to 5 years. Restoration was not consistently associated with higher patient-reported outcome measures; most studies reported comparable outcomes across restoration groups and alignment phenotypes.
Key findings
- The review included 13 studies: 1 randomised trial, 1 prospective registry-based study, and 11 retrospective cohorts.
- Follow-up ranged from 1 to 5 years.
- Most studies found comparable patient-reported outcomes regardless of CPAK phenotype, JLO, or aHKA restoration.
- Studies reporting better outcomes with restoration were limited and showed small effect sizes amid substantial heterogeneity.
Why it matters
Coronal alignment restoration is one proposed approach to improving outcomes after primary knee replacement. This review indicates that current evidence does not establish a consistent patient-reported benefit from restoring CPAK phenotype or its components. The findings help frame alignment decisions against the uncertainty of outcome evidence, rather than assuming that restoration reliably improves how patients report their results.
What to keep in mind
Evidence was limited by retrospective study designs, small samples—particularly for valgus and uncommon phenotypes—and substantial heterogeneity in alignment strategies, restoration definitions, and outcome reporting.